The trend in the circuit protection industry is currently toward complete circuit protection which is accomplished by the addition of supplemental protection apparatus to standard overcurrent protective devices, such as molded case circuit breakers. In the past, when such auxiliary protection apparatus or other circuit breaker accessories were combined with a standard circuit breaker, the accessories were usually custom-installed at the point of manufacture. The combined protective device, when later installed in the field, could not be externally accessed for inspection, replacement or repair without destroying the integrity of the circuit breaker interior. An example of one such factory installed circuit breaker accessory is found in U.S. Pat. No. 4,297,663 entitled "Circuit Breaker Accessories Packaged in a Standardized Molded Case", which patent is incorporated herein for reference purposes.
A more recent example of a circuit breaker including additional accessories is found in U.S. Pat. No. 4,622,444 entitled "Circuit Breaker Housing and Attachment Box" which allows the accessories to be field-installed within the circuit breaker without interfering with the integrity of the circuit breaker internal components. This is accomplished by mounting the accessories within a recess formed in the circuit breaker enclosure cover.
An electronic trip actuator which is mounted within the circuit breaker enclosure is described within U.S. patent application Ser. No. 862,929 filed May 14, 1986 and entitled "Trip Actuator for Molded Case Circuit Breakers". The circuit breaker actuator responds to trip signals generated by an electronic trip unit completely contained within a semi-conductor chip such as that described within U.S. Pat. No. 4,589,052. The development of a combined trip actuator for both overcurrent protection as well as accessory function is found within U.S. patent application Ser. No. 882,989 filed July 7, 1986 and entitled "Combined Trip Unit and Accessory Module for Electronic Trip Circuit Breakers". The aforementioned U.S. Patent Applications and U.S. Patent which represent the advanced state of the art of circuit protection devices are incorporated herein for reference purposes.
When one of such accessories is field-installed within the integrated protection unit cover, it is important that the accessory components are not removed or tampered with once the integrated protection unit is installed within an electric circuit. One purpose of the instant invention accordingly, is to provide field access facility to an integrated protection unit to allow selected accessory features to be readily installed before the integrated protection unit is connected within an electric circuit while later preventing access to such accessory components when the integrated protection unit is connected within the electric circuit.